Not sure if this is the right topic to put this under, but here goes:
I December I finished my first DPMS patterned 308AR. 16”, mid length gas with:
American Made Tactical Gen 1 80% lower.
Aero Precision barrel
Veriforce Tactical buffer assembly with 7” deep tube, 2.5” buffer (3.7 oz), spring
Aero Precision M5 upper
LaRue MBT-2S trigger
Magpul PMAG 10 LR/SR GEN M3 10 round magazines
Adjustable gas block
Shot it a few weeks ago and found I had successfully made a single shot 308AR. A single round loaded in the magazine to adjust the gas block would only feed about half the time on bolt release. The bolt started to feed the round, then would ride up over it, jamming it at an angle between the magazine and the chamber. When it would feed and fire it always ejected the empty case but never locked the bolt back, even with the gas block wide open. Textbook under-gas symptom.
I searched this site and found a treasure trove of information. Here’s a list of what I found and corrected:
Barrel gas port was 0.073”. Opened it up to 0.085
Ejector was square faced. Replaced with round faced
Replaced the 3.7oz buffer with a Heavy Buffers 5.5oz buffer with spring. I also ordered a 5.3oz KAK buffer and an orange spring from Springco. Why? The buffers are different lengths. The Heavy Buffers is 2.6” long and the KAK is 2.5” long. Not much room between the bolt catch and the bolt (~0.1”) with the Heavy Buffer. I didn’t know if it would make a difference and any extra parts just go in the next build.
Replaced the bolt catch. The one that came with the LPK might have been from an AR15 as it barely caught on the bolt when manually operated. See pics. I installed an Aero Precision bolt catch that works much better.
Ordered Lancer magazines. At least they would reliably feed a round on bolt catch release.
Shot 2 days ago. The heavens opened up and the angels were singing. Everything functioned perfectly. I started with the Heavy Buffers buffer and adjusted the gas block to that. Locked back every time. Went to the KAK buffer. Same thing. Perfection. In the interest of science, I installed the 3.7oz buffer and its included spring. I only shot 2 rounds, but it worked perfectly too. I went back to the KAK buffer and orange spring and enjoyed the rest of the shoot. I used Wolf 150gr FMJ and Fiocchi 150gr SST’s. Gas block adjustment was the same. Armed Doc, I’m heading your way in May to break in my new rifle on some hogs. I’ll be at a wide place in the road called Tennessee Colony. Hope they are active.
Besides passing along my learning experience, I wanted to say thank you to all who developed and maintain the information on this site. You have blazed one hell of a trail here and I’m just glad I could follow. The answers are usually here. Just read. And if the answer isn’t here, you guys give great troubleshooting advice to get to the answer. Just listen. Thank you again.